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/* Assumptions: - if device has no dev->hard_header routine, it adds and removes ll header inside itself. In this case ll header is invisible outside of device, but higher levels still should reserve dev->hard_header_len. Some devices are enough clever to reallocate skb, when header will not fit to reserved space (tunnel), another ones are silly (PPP). - packet socket receives packets with pulled ll header, so that SOCK_RAW should push it back. On receive: ----------- Incoming, dev->hard_header!=NULL mac_header -> ll header data -> data Outgoing, dev->hard_header!=NULL mac_header -> ll header data -> ll header Incoming, dev->hard_header==NULL mac_header -> UNKNOWN position. It is very likely, that it points to ll header. PPP makes it, that is wrong, because introduce assymetry between rx and tx paths. data -> data Outgoing, dev->hard_header==NULL mac_header -> data. ll header is still not built! data -> data Resume If dev->hard_header==NULL we are unlikely to restore sensible ll header. On transmit: ------------ dev->hard_header != NULL mac_header -> ll header data -> ll header dev->hard_header == NULL (ll header is added by device, we cannot control it) mac_header -> data data -> data We should set nh.raw on output to correct posistion, packet classifier depends on it. */ /* Private packet socket structures. */ struct packet_mclist { struct packet_mclist *next; int ifindex; int count; unsigned short type; unsigned short alen; unsigned char addr[MAX_ADDR_LEN]; }; /* identical to struct packet_mreq except it has * a longer address field. */ struct packet_mreq_max { int mr_ifindex; unsigned short mr_type; unsigned short mr_alen; unsigned char mr_address[MAX_ADDR_LEN]; }; #ifdef CONFIG_PACKET_MMAP static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing); #endif static void packet_flush_mclist(struct sock *sk); struct packet_sock { /* struct sock has to be the first member of packet_sock */ struct sock sk; struct tpacket_stats stats; #ifdef CONFIG_PACKET_MMAP char * *pg_vec; unsigned int head; unsigned int frames_per_block; unsigned int frame_size; unsigned int frame_max; int copy_thresh; #endif struct packet_type prot_hook; spinlock_t bind_lock; struct mutex pg_vec_lock; unsigned int running:1, /* prot_hook is attached*/ auxdata:1, origdev:1; int ifindex; /* bound device */ __be16 num; struct packet_mclist *mclist; #ifdef CONFIG_PACKET_MMAP atomic_t mapped; unsigned int pg_vec_order; unsigned int pg_vec_pages; unsigned int pg_vec_len; enum tpacket_versions tp_version; unsigned int tp_hdrlen; unsigned int tp_reserve; #endif }; /* * Create a packet of type SOCK_PACKET. */ static int packet_create(struct net *net, struct socket *sock, int protocol) { struct sock *sk; struct packet_sock *po; __be16 proto = (__force __be16)protocol; /* weird, but documented */ int err; if (!capable(CAP_NET_RAW)) return -EPERM; if (sock->type != SOCK_DGRAM && sock->type != SOCK_RAW && sock->type != SOCK_PACKET) return -ESOCKTNOSUPPORT; sock->state = SS_UNCONNECTED; err = -ENOBUFS; sk = sk_alloc(net, PF_PACKET, GFP_KERNEL, &packet_proto); if (sk == NULL) goto out; sock->ops = &packet_ops; if (sock->type == SOCK_PACKET) sock->ops = &packet_ops_spkt; sock_init_data(sock, sk); po = pkt_sk(sk); sk->sk_family = PF_PACKET; po->num = proto; sk->sk_destruct = packet_sock_destruct; sk_refcnt_debug_inc(sk); /* * Attach a protocol block */ spin_lock_init(&po->bind_lock); mutex_init(&po->pg_vec_lock); po->prot_hook.func = packet_rcv; if (sock->type == SOCK_PACKET) po->prot_hook.func = packet_rcv_spkt; po->prot_hook.af_packet_priv = sk; if (proto) { po->prot_hook.type = proto; dev_add_pack(&po->prot_hook); sock_hold(sk); po->running = 1; } write_lock_bh(&net->packet.sklist_lock); sk_add_node(sk, &net->packet.sklist); sock_prot_inuse_add(net, &packet_proto, 1); write_unlock_bh(&net->packet.sklist_lock); return(0); out: return err; } |
